1. Field of the Invention
The present invention relates to an object, a method, or a manufacturing method. The present invention relates to a process, a machine, manufacture, or a composition of matter. In particular, one embodiment of the present invention relates to a semiconductor device or a method of manufacturing the semiconductor device.
In this specification and the like, the term “semiconductor device” means all devices that can operate by utilizing semiconductor characteristics. An electro-optical device, an image display device (also referred to as display device), a semiconductor circuit, a light-emitting device, a power storage device, a memory device, or an electronic device include a semiconductor device in some cases.
2. Description of the Related Art
A technique in which a transistor is formed using a semiconductor layer has attracted attention. The transistor is used in a wide range of electronic devices such as an integrated circuit (IC) and a display device. As semiconductor materials applicable to the transistor, silicon-based semiconductor materials have been widely used, but oxide semiconductors have attracted attention as alternative materials.
Formation of an oxide semiconductor film having crystallinity has been studied. For example, according to Non-Patent Document 1, an InGaO3(ZnO)5 thin film is formed by a PLD method over a single crystal thin film of ZnO formed over a YSZ substrate, and subjected to heat treatment at 1400° C. to have a single crystal structure. Furthermore, according to Patent Document 1, the following technique is applied to a transistor: a first oxide member is formed over a substrate; first heat treatment is performed thereon to cause crystal growth from the surface to the inside and form a first oxide crystalline member, a second oxide member is formed over the first oxide crystalline member; second heat treatment is performed thereon to cause crystal growth using the first oxide crystalline member as a seed and form a second oxide crystalline member.